When grain is harvested and is hauled to a storage area or to the grain buyer's place of business it has many impurities mixed in with it such as grain hulls, dirt, weed seed, insects, etc. These impurities, of course, affect the quality of the grain and if the impurities are high in concentration, the buyer may dock the price it is willing to pay the seller for the grain a certain amount. Therefore, it is desired by the seller to remove as many of the impurities as possible. The seller in the above situation is usually the farmer who harvested the grain.
There are times when the farmer or a third party buyer wants to clean the grain even though the grain is not going to be involved in an immediate sales transaction. One example of this is when the grain is to be dried while it is stored. Often it is desirable to clean the grain before drying since the foreign material mixed in with the grain, if smaller than the grain, will fill the voids between the grain particles, interfering with the air flow through the grain.
If these small foreign materials are not removed from the grain before it is stored, "hot spots" may develop within the grain causing damage to the grain. Also, the drying operation is not conducted as efficiently as when the foreign material is first removed from the grain. More power per bushel of grain will be required to dry the grain if the foreign material is not first removed from the grain.
Often the third party buyer of the grain wants to remove some impurities from the grain. This may occur upon acceptance by the buyer of grain containing impurities or after grain that has been stored for a while is to be shipped and impurities such as dust have settled in with the grain during storage.
The grain must be clean of impurities for a number of reasons in addition to the reasons discussed above; to prevent the spreading of weed seed, to get a high quality grain that can be specially treated for planting, to provide a grain that is ready for processing to produce grain based products, to prevent the spreading of harmful insects, etc. Therefore, it is important to have a grain cleaning device which is effective in removing impurities from the grain passing through it.
Also, most grain handling operations are high volume operations. Therefore, it is very desirable that the grain cleaner be capable of continuous action and be able to handle a high volume of grain per time unit.
Some prior art devices have been devised for separating impurities from grain that have involved the use of air. Exemplary of these devices are the devices disclosed in the following U.S. patents:
______________________________________ U.S. Pat. No. Patentee Date of Issuance ______________________________________ 152,012 Schmitt June 16, 1874 619,482 Higginbottom February 14, 1899 806,821 Meyer December 12, 1905 988,796 Franklin April 4, 1911 1,416,489 Merzenich May 16, 1922 1,686,107 Sewell October 2, 1928 1,706,800 McWilliams et al March 26, 1929 2,931,500 Andren et al April 5, 1960 ______________________________________
However, none of these prior art devices put the grain in air suspension to remove impurities from the grain or regulate the air flow by air holes and adjustable covers for the air holes in the grain cleaner housing. Also, these devices do not accelerate the grain as it passes therethrough. Rather, these prior art devices use air along with some other method as the means for separating the impurities from the grain. Because of this, none of the prior art devices would be particularly effective and efficient at performing the function of removing impurities from grain.
From the above, it is apparent that there is a need in the art for a grain cleaning device which effectively and efficiently removes impurities from grain using aspiration as the only separating method. This invention fulfills this need, along with the other needs which will become apparent to the skilled artisan once given the following disclosure: